3 or 4 pounds is about max, We did drop 8 pounds at one time from my big jordan several years ago. With the candy bag at 400'. The candy spread far and wide. Kids were picking up candy all afternoon.
What kind of bag are you using? I've seen the big tube sock type plug up. When the sock is released the candy seems to just ball up and gets held in place by the fabric tension. Then you have to start tugging the line to get it to drop. I use the flat cloth stlye that drops every time.

My bag is 24" square when laid flat. The edges are all hemmed, a eyelet is at each corner. At one coner is a piece of string attached clove hitched to one eylet with a loop at the end of it. This gets threaded through the other 3 eyelets forming the bag, hook the loop too your drop release. At the very center of the bag I've sewed a loop and attatched a string to it maybe 2ft long. the other end of the string is tied to the dropper it self. I'll bring my dropper to decatur, we can compare notes.

Thanks Tony for the info. I ended up making my bags around 30in long and about 8in wide when laying flat. With making it a tube I will be able to pull the top of the bag when hung upside down up to the release. In theory anyway. We will see tomorrow.